1. Technical Field
The present disclosure relates to a method for producing a Group III nitride crystal, and an apparatus for producing the same.
2. Description of Related Art
A Group III nitride crystal has been utilized in a heterojunction high energy electron device, such as a field of a power semiconductor, and a photoelectronic device, such as an LED and a field of laser. As a production method of a Group III nitride crystal, an oxide vapor phase epitaxy method using a Group III oxide as a raw material has been developed (see, for example, JP-A-2009-234800).
The reaction system in the oxide vapor phase epitaxy method is as shown below. Ga2O3 is heated, and hydrogen gas is introduced thereto. The hydrogen gas (H2) thus introduced is reacted with Ga2O3 to form Ga2O gas (the following reaction scheme (I)). Ammonia gas is then introduced thereto and reacted with Ga2O gas thus formed, thereby forming a GaN crystal on a seed substrate (the following reaction scheme (II)).Ga2O3+2H2→Ga2O+2H2O   (I)Ga2O+2NH3→2GaN+H2O+2H2   (II)
However, there have been cases where a nitrogen element-containing gas, such as ammonia gas, is thermally decomposed in the process of introducing. In these cases, a shortage of ammonia as a nitrogen element-containing gas may occur due to the thermal decomposition in the reaction scheme (II), and the amount of GaN as a Group III nitride crystal formed may be decreased, which results in the deterioration in productivity.